Field-Repairable Coupling for Non-Collinear Shafts
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Solution Overview
Problem
Conventional couplings for connecting non-collinear shafts fail in high-temperature, corrosive environments due to rapid wear of needle bearings and the need for frequent replacement, which is costly and difficult to maintain, especially in applications like industrial ovens where specific materials are required for safety and durability.
Innovation Solution
A coupling design featuring offset yokes and a knuckle with bushings and threaded pins that allows for easy disassembly and field repair, using stainless steel and carbon-filled polyether etherketone (PEEK) components for durability and resistance to high temperatures, enabling adjustment and replacement of wear parts without replacing the entire coupling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional needle bearings and pin-hole wear points are used in couplings, then the coupling can connect non-collinear shafts with angular flexibility, but the coupling fails rapidly in high-temperature and corrosive environments due to lubrication breakdown and wear
Solution Approach 1:
The patent changes the material parameters and operating conditions by replacing needle bearings with bushings that operate without lubrication, and using stainless steel and carbon-filled PEEK materials that maintain their properties in high-temperature environments. This eliminates the lubrication breakdown issue that plagues conventional couplings in harsh environments.
Solution Approach 2:
The patent employs composite material construction, specifically carbon-filled polyether ether ketone (PEEK) bushings combined with stainless steel components. This composite approach provides both the wear resistance needed for durability and the chemical inertness required for corrosion resistance in high-temperature and corrosive environments.
2Reliability
If the entire coupling is replaced when pins wear and holes elongate, then proper fit and function are restored, but maintenance costs increase significantly
Solution Approach 1:
The patent segments the coupling into replaceable modular components - specifically, the bushings can be independently replaced without replacing the entire coupling. This is achieved through the design where bushings are positioned in openings of the knuckle and can be accessed and replaced individually, allowing only the worn components to be replaced rather than the entire assembly.
Solution Approach 2:
The patent enables selective replacement of worn bushings while retaining the knuckle, yokes, and other serviceable components. This discarding and recovering approach allows the valuable structural components to be reused while only replacing the consumable bushing elements, significantly reducing material loss and maintenance costs.
3Ease of repair
If the coupling is disassembled to allow shaft removal for maintenance, then access to internal components is gained, but the immovable components on either side prevent needle bearing style couplings and complicate the design
Solution Approach 1:
The patent extracts the needle bearing functionality and replaces it with bushings that are integrated into the knuckle structure. This extraction allows for easier access and replacement - the bushings can be removed and replaced without requiring complete disassembly of the coupling or removal of shafts, simplifying the maintenance process while maintaining the structural integrity required by immovable components.
4Reliability
If stainless steel and carbon-filled PEEK components are used, then resistance to high temperatures and corrosion is improved, but material selection becomes more restricted
Solution Approach 1:
The patent establishes specific material parameter requirements - stainless steel for structural components and carbon-filled PEEK for bushings - that are optimized for high-temperature and corrosive environments. These parameter specifications ensure consistent performance in harsh conditions while providing clear material selection criteria that balance reliability with manufacturing practicality.
Data Source
AI summary
A method for servicing a coupling connecting two non-collinear shafts, which coupling includes a pair of sleeves each having a yoke provided at an end portion thereof, a knuckle provided between each yoke that includes a body having a plurality of openings, a plurality of bushings each positioned in one of the openings, and a plurality of separate pins threadingly engaged to the yokes for releasably connecting the yokes to the knuckle. The method includes loosening a pair of opposed pins on one of the yokes such that an end portion of each pin is spaced from the corresponding bushing, which disengages that yoke from the knuckle, separating the disengaged yoke from the coupling, removing a worn bushing, inserting a different bushing in the opening, positioning the yoke to reengage the knuckle and tightening the pins on the yoke until the end portion of each pin engages the corresponding bushing.